Spring system



A118. 22, 1950 R. SAULNIER 2,520,017

SPRING SYSTEM Filed Oct. 6. 1945 13 SheetQs-Sheet 1 B 1 Iwvgrzfqrx- Allarnqys R. SAULNIER SPRING SYSTEM Aug. '22, 1950 13 Sheets-Sheet 2 Filed Oct. 6, 1945 Filed Oct. 6'. 1945 1:5 Shegts-Sheet 3 g- 22, 1950 R. SAULNI.ER 2,520,017

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SPRING SYSTEI Filed Oct. 6, 1945 13 Sheets-Sheet 4 ,dlforn y-s R. SAULNIER SPRING SYSTEM Aug. 22, 1950 13 Sheets-Sheet 5 Filed Oct. 6, 1945 1950 R. SAULNIER 2,520,017

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' SPRING SYSTEM Filed Oct. 6. 1945 I 13 Sheets-Sheet s Aug. 22, 1950 R. SAULNIER 2,520,017

smmc SYSTEM Filed Oct. 6. 1945 13 Sheets-Sheet 9 Afforn eye 22, 1950 R. SAULNIER 2,520,017

SPRING SYSTEM Filed Oct. 6, 1945 l3 Sheets-Sheet 10 7 W P W flifarrze ys g- 2 1950. R. SAULNIER 2,520,017

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Aug. 22, 1950 R. SAUL-NIER 2,520,017

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SPRING SYSTEM 7 Filed Oct. 6. 1945 15 Sheets-Sheet 15 diZbrnpys Patented Aug. 22, 1950 OFFICE SPRING SYSTEM Raymond Saulnier, Paris, France Application October 6, 1945, Serial No. 620,749 In France April 17, 1944 I Section 1, Public Law 690, August 8, 1946 Patent expires April 17, 1964 7 Claims.

The present invention relates to devices including a flexible structure the deformations of which under the effect of the external forces are to be controlled. The invention is more especially, but not exclusively, concerned with devices of this kind (such as suspension springs, resilient wheels, transmissions, clutches, etc) in which the structure in question is to keep always its circularshape in the course of these deformations, which are therefore reduced to variations of radius of the circle constituted by said structure.

It has already been proposed to obtain this result by a discontinuous construction of the structure in question the various elements of which, while being movable radially so as to permit the desired variations of its radius of curvature, can slide circumferentially with respect to one another in order to make allowance for the corresponding variations of length of the structure. Such devices are complicated and are lacking in resiliency. Furthermore, due to the discontinuity of their peripheral surface, they cannot be employed in many applications.

It has been endeavoured to obviate these drawbacks by constituting the structure in question in the form of an element continuous and extensible in the tangential direction. But such devices do not constitute true solutions of the problem above set forth, because their periphery does not present, at every point thereof, the desired resistance and continuous curvature.

The present invention has for its object to give an accurate solution of the above problem. It consists essentially in constituting the structure in question by a non-extensible flexible, self-sus- 'taining blade or band, curved to the desired shape, and carrying, rigidly fixed at a plurality of points thereof, arms connected, for instance by pivoting at suitable points, to a common central piece, the disposition and the dimensions of these various elements being chosen in such manner that the deformations of the structure under the action of the external forces to which it 1s subjected are fixed by a predetermined law.

As above stated, the invention, in one form thereof, has for its object to ensure that a flexible band wound into a circle is kept in this circular form in the course of the deformations it undergoes.

In this case, the desired result can be obtained, for a given range of deformations chosen within suitable limits, by pivoting the above mentioned arms to the common central piece at respective points located. on this piece. along a hyperbolic spiral such that its parameter, that is to say the distance between its pole and its asymptote, is equal to the radius of the circle formed by the band in its mean position, said arms, in the mean position of the system, being tangent to the spiral in question.

In such devices, the flexible band, in the course of its deformations, always has its center located at the same point of the central piece, to wit the pole of the hyberbolic spiral traced thereon. This property permits many different arrangements of the piece and the band with respect to each other. It permits, in particular, of pivoting the central piece about the center of the structure constituted by the flexible band, for instance, in the case of a flexible wheel, about the axle of this wheel. It also permits of making use of several central pieces associated with the same flexible band, the points utilized on each piece being only those corresponding to an interesting portion of the hyperbolic spiral. In this case, the various central pieces associated together must in general be pivotally mounted with respect to one another about an axis passing through the poles of their respective spirals. However it is possible, according to a particular embodiment of the invention, to make use of a double central piece the two elements of which are fixed with respect to each other, provided that the two hyperbolic spirals traced on these respective elements have the same pole and the same asymptote, but are wound in opposed directions, that is to say are symmetrical of each other with respect to their common polar axis.

The particular embodiment of the invention according to which the flexible band is caused always to keep a circular form gives considerable advantages in a very great number of applications.

In the construction of resilient wheels for vehicles, it permits of absorbing the load by means of a single spring.

In.the application to springs, in particular, it permits of substantially reducing the overall dimensions of the system, and, owing to the uniform curvature of the band over its whole length for all service loads, it ensures uniformity of fatigue of the band over its whole length.

On the other hand, it will be readily understood that the construction of brake drums, clutch elements, electric contactors, expansible pulleys, and analogous parts for which it is necessary to keep a strictly circular shape, will be made particularly simple and emcient when applyingthe above stated principle. according to the invention.

The same applies to the guiding of springs oi circular shape in order to obtain. for a given variation of radius, a given displacement of one end thereof.

It should be well understood that if, in many cases, the arms above mentioned must be as rigid as possible, this is not'an absolutely necesary condition according to the invention. In particular, the latter includes the case in which the arms are fixed in a rigid way at one end of the flexible band and at the other end to the common central piece, which of course implies that these arms must then be flexible.

Other features and advantages of the invention will appear in the course of the following description, with reference to the annexed drawings, of various embodiments of the invention, given by way of example.

- Onthese drawings:

Fig. 1 is a diagrammatic elevational view of a first embodiment oi the invention, adapted to be applied to the construction of a resilient wheel;

Fig. 2 is a similar view of another embodiment;

Figs. 3, 4 and 5 show, in a similar way, modifications of the embodiment of Fig. 2;

Figs. 6, 7 and 8 illustrate the application of the invention to the. construction of suspension springs;

Fig. 9 shows a suspension for a bicycle trailer made according to an embodiment of the invention,

v Figs. 10, 11 and 12 are partial views relating to modifications of vehicle suspensions made according to the invention; I

"Figs. 13, 14 and 15 are, respectively, a sectional view, a part elevational view, and a part sectional view on an enlarged scale, of an embodiment of the invention as applied to the construction of a clutch;

Fig. 16 shows an electric contactor according to the invention;

Fig. 17 is a diagrammatical view of free-wheel device made according to the invention;

Fig. 18 shows a motion reducing link mechanism according to the invention;

Figs. 19 and 20 are views illustrating means for guiding the deformation of circular springs according to the invention;

Figs. 21 and 22 are diagrammatical views relating to a particular embodiment of the invention intended to reduce the space occupied by the device;

Figs. 23 and 24 are, respectively, a diagrammatical view in radial section, and a side elevational view, of an elastic tire made according to the principle of the invention;

Figs. 1 to 24 inclusive relate to the particular form of the invention according to which a flexible deformable band must be compelled always to keep a circular shape.

The invention is, in this based upon the characteristic property of hyperbolic spirals, to wit the constant length of the circular arc subtended between said spiral and its polar axis, in combination with the property of circles according to which the radius makes a constant angle with the circumference.

The consequence of the first property is that, being given a certain number of spirals having the same pole and the same polar axis, all the circular arcs that have their center at this pole and are limited by two of these spirals are of the same length.

It follows that, if a certain number of points. sufiiciently close to one another, of an elastic band are guided in such manner as to be able to move freely along respective hyperbolic spirals, having all the same pole and the same polar axis, and if, on the other hand, the band, at these points, is compelled to remain always perpendicular to the corresponding radii traced from the common pole of all the spirals, this band, when subJected to the action of external forces, will deiorin concentrically to itself, while turning, dinerentially along its circumference, about the pole, until, due to its new curvature and to the resulting internal strain, it finds a new state of equilibrium, while still preserving its circular shape.

The invention thereiore consists, in the form of the invention that is being considered, in providing, in combination, means for guiding a certain number of points of the band along hyperbolic spirals having all the same pole and the same polar axis and means for compelling the normals to the band at these various points to pass always through said pole.

Fig. 1 shows a rigorously accurate application of this principle, while Figs. 2 to 22 inclusive relate to solutions that are approximate, but sufficiently accurate for practical purposes.

In the embodiment of Fig. 1, I is the flexible band wound in the form of a circle and the ends of which overlap at la. The above mentioned points of this band are: 90, pl, pa, in. 94-

Point pa is to be guided along a hyperbolic spiral which coincides with the polar axis passing through the center 0 of the circle and through said point no.

Point 171 must move along a hyperbolic spiral the pole of which is II and the polar axis Ops. Therefore the equation of this hyperbolic spiral is:

in which (n is equal to the length of arc pan (parameter), p represents the polar all; tips and n is the angle po-L-m.

Point 9: must be guided along a hyperbolic spiral the pole of which I and the polar axis In. and the equation of which is:

in which as is equal to the length of arc Pops.

Likewise, points 12: and p4 must be guided along hyperbolic spirals both having as pole I and as polar axis 0pm. and the respective equations of which are:

a: and a4 being respectively equal togthe lengths of arcs pop: and mp4.

In the embodiment of Fig. 1, which will be supposed to represent a resilient wheel, the guiding means in question are constituted as follows: band i carries, fixed thereto, at each of the points in. in. 9:. Pa. in, an arm 2 provided at its end with a fork 4 adapted to slide on the axle I of the wheel. This axle carries a huh I which constitutes the common central piece and is free to rotate about the. axle. This hub is connected through radial arms I with an annular part I. Each of the arms 2 carries a pin, respectively 9o, 91, 9:, la, 94, located at a distance from the corresponding point no. in. in. m. in equal o I length b. The annular part I of the hub is provided with slots 81, 8:, 8:, 84 the shape of which corresponds to the following equations (slot lo being rectilinear and extending along the polar axis In):

It will be seen that, owing to this guiding, the corresponding points no, in. pa, pa, m are truly compelled to move, under the effect of the load, along the above mentioned hyperbolic spirals.

Furthermore, due to the fact that arms 2 have been built perpendicular to band I at their respective points of fixation, they constitute the second means above mentioned, to wit those which compel the normals to the bands at the various points that are considered to pass always through center 0.

I have therefore truly provided a device complying in a rigorous manner with the conditions above set forth. Under these conditions, band I will always keep its circular shape in the course of its deformations, as shown in dotted lines on the drawing. In the course of the deformation that brings each of the points pa, 111, pa, 1):, P411) to positions p'o, p'i, 9'2, 9'3, pi', each point of the It is therefore clear that the device diagrammatically shown by Fig. 2, due to the fact that it practically complies with the conditions above set forth, preserves the circular shape of band I in the course of the deformations thereof under the effect of variations of the external forces that are applied thereto. If, for instance, the wheel of band turns, with respect to center 0, through an I angle which is the greater as the point in question is more remote on the circumference from point 90.

In order to obtain a device of simpler construction and safer operation, it suffices to comply with the conditions above set forth with a certain approximation.

An example of such a. device is shown on Fig, 2, which is a diagrammatical elevational view of a resilient wheel made according to the invention.

In this case, in order to obtain the guiding of the various points 10 of the band I along the desired hyperbolic spirals, all having I! as pole and IX as polar axis, it is considered that the portions of these spirals effectively described by these points may coincide with circular arcs of suitably chosen centers. According to the embodiment of the invention shown by Fig. 2, these centers are distributed, on apiece I3 carried by the axle I of the wheel, along a hyperbolic spiral the pole of which is 0, the axis of which is BY, perpendicular to 0X, and the parameter of which is equal to the radius of the circle formed by'band I in its mean position. On the other hand, in order to cause the various points p to describe these circular arcs, use is made of arms I2 fixed in band I, the angles of fixation being such that, in the means position of the system, these arms are tangent to the hyperbolic spiral the pole of which is 0 and the polar axis OY, at the points thereof where said arms are pivoted to piece I3.

. I have ascertained that, under these conditions, not only do the various points p of the band describe circular arcs which, within the limits of deformation that are considered, may be considered as coinciding with portions of spirals having I as pole and IIX as polar axis, but also the fixation of the various arms I2 in band I compels the normals to said band at points p to pass all through point 0, at least with an approximation suflicient for practical purposes.

Fig. 2 undergoes an increase of load, the arms I2 pivot about their respective points 0 and their ends 9 move to p, the whole taking the position shown in dotted lines, which corresponds to a reduction of the diameter of the wheel, the rim of which passes from position I to position I. The front end of the elastic band turns along the circumference of the circle, from position Ia to position Ia, and all the other points of said band also turn about center II through different angles, smaller and smaller as one gets farther from point In along the circumference in the counterclockwise direction, as shown by Fig. 2, that is to say as the corresponding arms I2 pivot on central piece I3 at points farther and farther from pole II.

An important property of the device which has just been described lies in the fact that, in the course of its deformations, circle I always has its center coinciding with the pole 0 of the spiral, traced on piece I3, along which are located the pivot points 0 of arms I2.

In the case of Fig. 2, it is supposed that the central piece I3 (hub of the wheel) which carries the pivot axes c of arms I2 is fixed with respect to axis 0. However, it is possible to provide other arrangements. Furthermore, instead of making use of only one central piece, it may be advantageous in many cases, to provide two or several pieces arranged in such manner as to cooperate with the same flexible band.

Fig. 3 shows an embodiment in which the axis it carries, pivoted thereon, two central pieces Ila and IS!) on the periphery of which are pivoted arms In and I2b fixed in the metallic band I. One of the arms I21; and one of the arms I2b are Joined to each other at their point of fixation pa to the band I. a With this arrangement, under the effect of any cause tending to deform the wheel,the arms In and IN) turn about their respective pivot axes Ca and on at the same time as the pieces I31: and I3b turn with respect to each other about the axle 3 of the wheel. Under the effect, for instance, of an increase of the load, band I comes into position I', while the various arms assume positions I2'a and I2'b.

As a rule; as shown by the example of Fig. 3 when several central pieces are 'used, they must be free to turn with respect to one another about the axis of axle 3.

However, it is possible, in some cases, to make use of two central pieces fixed with respect to each other, which cooperate, through their respective arms, with the same flexible band. An example of such a construction is shown on Fig. 4. In this case, the hyperbolic spirals traced on the common central piece I3c, along which are located the pivot axes Ca and cs of the arms I2 must be two spirals identical and symmetrical to each other, with respect to their common polar axis. The band I, instead of winding or unwinding from the overlap point a, winds or unwinds symmetrically from a point Is diametrically opposed to point la. In Fig. 4, as in the other figures, is shown in clot-and-dash lines the position of the wheel under the effect of an increase of the load or of a shock on the ground.

Fig. 5 shows a particular embodiment of the 1 arrangement of Fig. 4. In this case, only two points on each hyperbolic spiral are taken as pivot axes of arms I2. One of these points I4 is the point of intersection of he two spiralsfithe two other points Ila and Ilb being any two points symmetrical to each other on the two respective spirals. In keeping strictly to the arrangement shown by Fig. 4, the arms In and Ilb corresponding to pivot points its and III: would extend directly between these points Ito and lit and the corresponding points p. and pa of the band I. In order to ensure perfect correspondence of the displacements of the ends of said band I which come to Join with each other at h, the lower arms Ila and lib are given an angular shape, the apexes of their right angles being joined by a connection which permits displacement of the whole. For instance, as shown by Fig. 5. arm Ila is provided with a slot I1 and arm lib with a finger or pin I la engaged in this slot II. Thus, the parts of band I to which lead the arms In and I to in question are always kept in coincidence with each other, that is to say the circle formed by the band I always closes exactly upon itself.

Up to now, it has been supposed that the devices described with reference to the drawings were wheels. It should be well understood that the invention is not in any way limited to the construction of resilient wheels and that it covers, in a general way, any device including a flexible blade or band adapted to be more or less curved. while keeping always the shape of a circle or of a circular arc (the expression "circular arc" ap plying to the case of an angle greater than 360' as well as to that of an angle smaller than this value).

The invention is particularly applicable to the case of the flexible band above mentioned constituting a spring. As a matter of fact, it will be understood that if a spring band is caused to remain constantly wound in the form of a circle. supposing, of course, that the thickness of this band is uniform, the'fatigue will be the same at all the points thereof and the efilciency of such a band will be maximum. Furthermore, for a given length of band, the winding thereof in the siderably reducing the space occupied, which is particularly interesting in the case of a vehicle suspension.

Fig. 6 gives an example of utilization of a spring according to the invention for the suspension of an axle, such as 3, with respect to a fixed part II. In this case, the band I is secured in its middle portion, to the fixed part I 0, while four at one end of the band I.

8 drawing. Inthiscaseitissuppoledthat suspended point is point II. chosen for The displacements thispointll,inthedirectionofthe (take place in such manner that band I always form of a circle or a circular arc permits of conremains of circular shape. By taking any other pointofband I orofoneofthearms Ilassmpended point, it is possible to obtain a great number of different combinations, that is to say to varyatwilltheamplitudeandthedirectionof the displacement of said suspended point.

Fig. 8 diagrammatically shows. by way of example, the construction of a structure of the type shown by Fig. 7, but in which the two upper arms I! are dispensed with. As, in this case. the upper portion of band I (extending over nearly 180') might undergo non-symmetrical deformations, the middle point It of this band caries an arm 2. adapted always to pass through the center of the circle; the lower end of arm ll carrying for instance a fork that slides on the axis I of the structure.

Figs. 9, 10, 11 and 12 show the application of the device according to the invention to the suspension of a vehicle, constituted for Instance by a bicycle trailer.

The embodiment of Fig. 9 includes a spring arrangement substantially of the type shown by Fig.7. Spring I isfixedtothebodyofthevehicle through arms I! pivoting about points distributed on the periphery of a central piece II fixed to said body, and the suspended part. that is to say the stub axle 21 of the wheel, is mounted on one of the ends of band I. The suspension of Fig. 9 is constituted by a system (including spring I, with its arms I! and central piece II) adapted to be fitted at will on any vehicle body. For this purpose, central piece II is constituted by. a plate provided with a certain number of holes 30 by means of which it can be fixed in any desired position on a vehicle body. With a suitable choice of the position and direction of plate It with respect to the body, it is possible to obtain any desired amplitude and trajectory of the displacements of stub axle 21.

Fig. 10 shows a vehicle of the same type as that of Fig. 9. but corresponding to a different geometrical conception .of the problem. In the embodiment of Fig. 10, a point II of band I isfixedtothebodyll whichcarriesthepivots of arms I2. Now, theabove explanations, together with Fig. 9, show that all the points of band I must, in the course of the deformations thereof, move with respect to the central piece.

points ofthis band are connected through arms II to a double central piece I3c of the type shown in particular on Figs. 4 and 5 above described, and which carries the axle 3 centered on the pole of the hyperbolic spirals materialized in this piece. In this way. the axle 3 is suspended in a position of equilibrium depending upon the com- 3 and the resiliency of band I. Within the permitted limits of displacement, any vertical displacement of axle 3 will correspond to an elastic deformation of band I, but the latter will always remain wound in the form of a circle.

In the embodiment of Fig. '7, the band I that bined actions of the load supported by the axle acts as spring is compelled to keep its circular form due 'to the fact that six of its points are connected through arms I2 rlxed therein to suitably chosen pivot points. located, as above expiained, on a fixed surface not shown on the 11, therefore, point II is fixed to the body, then the central piece should move with respect to the body so-that its pole. located at I for the position in solid lines, comes into I; for the position in dotted lines, that is to sa remains always at the center of the circle formed by band I. However, if it is supposed that the amplitude of deformation of band I is relatively small, it may be sumcient to pivot arms 32 directly I) body II and thus still to obtain a satisfactory solution. of course, in this case, the points where arms 8! are pivoted to the body and no longer located on a hyperbolic spiral traced on the body 2|.

According to the embodiment of Fig. 11. the body II of the trailer carries, fixed thereon as by bolts 24', the lower end of a rectilinear spring band 24, which is prolonged by a portion ll of circular shape. The portion II of the spring carries. fixed therein at difiermt points of its circumference, arms I! pivoted to central piece It IIatrespectivepointsorthepes-lpha' thareof,

with an arm 24 the end of which carries the axle 2'! of wheel 22.

When, under the effect of a shock for instance, axle 2'! tends to move upwardly with respect to body 2|, the arm 28 which carries this axle pivots in the clockwise direction about axis 22, fixed with respect to the body. Central piece I3, which is rigid with arm 28, therefore turns also aboutthe pole of the spiral formed by its outline. It follows that the various points 1: of fixat on of arms I2 in the portion of the spring are drawn toward the center. and owing to the construction the principle of which has been above set forth, this portion 25 is deformed while remaining circular. The last point p onthe left of the drawing, that is to say where portion 25 is Joined to portion 24, can undergo the desired displacement owing to the bending of the branch 24 of the spring.

In the embodiment of Fig. 12, I is the flexible band acting as a spring. 21 the stub axle of the wheel 28 of a vehicle, 34 a lever carrying said stub axle and hinged at I! to an arm 36 rigidly fixed to the frame 31 of the vehicle, the axis about which arms 34 and 36 are pivoted to each other being located substantially at the center of the circle constituted by spring I in the mean position thereof. Arms I2a and I2b, fixed with respect to band I,'are carried by a double central piece I3, which is supported onl by arms I21: and

I2!) and consequently floats with respect to the remainder of the device. F'nally, in order to permit the working of the device. the stub axle 21 of the wheel is connected to the end of circle I through a shackle 39. This embodiment shows still another modification with respect to those above described and in which the central piece has been shown mounted in fixed pos-tion on the body of the vehicle (Fig. 9), then pivotally mounted on said body about the pole of the spiral (Fig. 11). This time, the central piece is wholly free with respect to the vehicle and is connected thereto only through the intermediate of arms I2a and I2b and of band I, one end of which is connected through arm 36 to the frame of said vehicle.

Figs. 13, 14 and 15 give an example of the application of the principle of deformation of a flexible band according to the invention to the construction of a clutch. This clutch is intended to couple at will a drivng shaft 40 with a driven shaft 4|. For this purpose, shaft 4| carries. slidable thereon, two frusto-conical elements 42 and 43 adapted to be a plied against the inner wall of a hol ow bod 44 of corresponding shape car-' ried by shaft 40. The principle of such clutches is well known and it sufllces to move elements 42 and 43 away from each other for bringing them into contact with element with a view to ensuring the drive of shaft 4| by shaft 40. For this purpose, according to the invention, elements 42 and 43 are subjected to the action of a circular spring band I of variable diameter provided inside the space between pieces 42 and 43 and the periphery of which comes to bear against the inner walls of said elements 42 and 43.

When the diameter of circle I is increased, the latter, acting obliquely on elements 42 and 43, wedges them away from each other and brings them into contact with part 44.

In order to obtain the desired expansion and retraction of the band I while always maintaining its circular shape. use is made of the principle applied in the above described embodiments of the invention and which consists in securing to spring band I several arms such as I21, I21, and I23, the inner ends of which are pivoted about points of the periphery (in the formof a p rbolic spiral) of a central piece I3 (Fig. 14), the pole of this spiral being on the axis of shaft 4| and said piece being free to rotate on this shaft.

In order to control the deformation of band I, one of the arms I2 rigid with this band (arm I2: in the embodiment illustrated) carries a lever 4| pivoting in a boss 43a of element 43 and the rotation of which is produced, in a known manner, by the sliding displacement, on shaft 4|, of a conical ring 41.

The explanations relating to the above described embodiments have shown that, when one of the arms I 2 is pivoted with respect to the central piece, there is obtained; according to the direction of rotation, an increase or a reduction of the circle diameter. Consequently, the rotation of arm |2a.in the desired direction, caused by the rotation of lever 46, rigid with this arm, moves pieces 42 and 43 away from each other and brings them into contact with part 44, which couples the driven shaft 4| with the driving shaft 40.

In order to avoid wedging of the band I between the inner walls of pieces 42 and 43, the band may be provided with rollers 45 located alternately on one side and the other of the middle plane of band I so that a part of these rollers bear upon piece 42 and the others on piece 43. Preferably, rollers 45 are fixed to band I at the ends of arms I2, that is to say where these arms are fixed to band I.

The embodiment of Fig. 16 shows the application of the invention to the construction of an electric contactor. In this case it is desired to obtain, between two metallic parts, an instantaneous contact along a surface as great as possible. The invention permits of obtaining this result by increasing the diameter of a circular band I located inside a casing 48 which constitutes one of the elements of the contactor, the other element being constituted by the band I itself. The guiding of this band is obtained by means of two common central pieces, one of which, I3a, carries thre pivoting arms I2a. fixed in band I. The other piece is not shown because it is reduced to a single point Cb on which is pivoted the arm I2 fixed in band I. This point is located on a spiral Sb, symmetrical with reference to a line I'IPb of the spiral Sa formed by the extension of the curve of piece I3a. This arrangement is of the type above described with reference to Fig. 3, in which central piece I3b would be fixed with reference to the axis of central piece I 3a and would be reduced to a single point 0b. The movement of piece I3a is imparted thereto by a lever 33 fixed thereto and, the rotation of which in the direction of arrow f1 produces contact, while, in the direction of arrow in, it breaks it. The switch might as well be controlled by acting on the system through any of.

the arms I2a and I2b.

Fig. 1'7 shows how the principle of the invention can be applied to the construction of a freewheel device. The part rigid withhub '49 includes a central piece I3, arms I2 pivoted to this piece and a circular band I to which these arms are secured. This band I is intended to cooperate with an annular member or ring 50 forming, for instance, the driving part of the free- 11 wheel, so that band I and ring 80 are wedged with respect to each other for one relative direction of rotation, whereas, for the opposite direction, they must be able to slide with respect to each other. Now, when the inner part rigid with hub ll turns, in the direction of arrow F, at a speed higher than. that of ring 50, the reaction imparts to band I a tendency to have its diameter reduced, whereby the system in question can turn freely with respect to ring II. On the contrary, when said system is subjected to a resisting torque, that is to say a torque in the direction opposed to arrow F, band I is caused, by friction, to turn in a direction which tends to increase its diameter. so that it is wedged against ring It and the latter therefore drives hub 49. Part BI is a balancing mass.

Fig. 18 shows an example oi another application of the invention, to wit the construction of a motion reducing link mechanism. This device includes a lever 52 for operating a rod ll hinged to one end of a circular band I of variable diameter, made according to the invention (and corresponding in particular to the embodiment illustrated by Fig. 2). The other end of said band carries. hinged thereto, a bar 54 pivoted to the lever I! which receives the reduced speed movement. The operation of this device results clearly from the above given explanations.

Figs. 19 and 20 are diagrammatical views showing two circular springs guided according to the principle of the invention, and arranged in such manner that, for a given variation of the radius, the displacement of the end of the spring that is acted upon has a given value, this value diflering according to which end of the spring is acted upon. Fig. 19 shows, in fact, that in order to obtain a radius variation corresponding to the radial distance between the full line I and the dotted line I', it is necessary to impart to end A an angular displacement AA much greater than that to be imparted to end B. The same is true for Fig. 20.

As a matter oi. fact, and as it had already been shown by Fig. 2. the value of this displacement is the greater as the arm I! carried by the end in question oi the spring is fixed to a point of the spiral nearer to the pole thereof. Fig. 19 clearly shows that the angular displacement of end A, which corresponds to a point of the spiral close to the pole I thereof is much greater than the angular displacement of point B, fixed to an arm I2 connected to a point of the spiral much more distant from II.

The embodiment of Fig. 20 gives analogous results for a diilferent angular disposition of the central piece, that is to say for different values of the distance of the pivot points of arm I! to the pole of the spiral.

In the preceding embodiments. except however in that shown by Fig. 1, the device is essentially constituted by a flexible and resilient band provided with arms secured in its periphery, these arms being pivoted, at suitable points, to a central piece. This arrangement may, in some cases. involve overall dimensions which are not acceptable.

The embodiments shown by Figs. 21 and 22 have for their object, within the scope of the present invention, to obviate thi drawback. They are based on the following remarks:

It will be supposed that, according to the above described solution, flexible band I has its deformation controlled by a certain number of arms shown in dotted lines at I2 and pivoted at Metentpointsofacentralpieceorspiraiflhho shown in dotted lines). According to the embodiment of Fig. 21, there is traced a spiral 81 parallel to 8 (that lg to say constituted by the envelope of a family of circles all of the same radius and having their centers on B). Arms II are then replaced by arms III also secured the elastic band I, but hinged at various poin of spirals S1, and these arms III are given. elasticity sufilcient for enabling them to be formedsoastopermitband I tocomeintoposition I. Fig. 21 shows that the radii of curvature of arms III-supposed to be all of thesamethickness-in the course of their various deformations. are the same for all of these arms, which indicates that they are working under identical conditions.

This Fig. 21 shows at it the arcs described by theendsofelasticarms Illandatll thearcs they would describe according to the solutions of the preceding embodiments, that is to say if class.

ticband I wasguidedbyri idarmssuchas II pivoted at various points of spiral S. It is found thatarcstlandtl areveryclosetooneanother and can be considered as practically coinciding.

The construction shown by Fig. 22 is based upon the same principle as that of Fig. 21. But in this case the flexible arms I20, instead of being pivoted at various points of a spiral, such as S1 traced on central piece Ila, are fixed in the periphery of said piece Ila, the outline of which corresponds to spiral 81. Examination 0! the arcs 60 and ti described by the ends of the arms lilo which are secured in band I shows that, with this arrangement, a suiilcient approximation is also obtained. This form of the invention might, in particular, be well adapted to the construction of resilient wheel shoes.

Figs. 23 and 24 show the application of the device according to the invention to the construction of a resilient tire for vehicle wheels.

In this construction, the tire is constituted by a series of elements such as E (Fig. 24) to be deformed transversely to the mean plane of the wheel. Fig. 23 shows how this deformation takes place. It will be seen that the resilient band I which forms an element of the tire, the section of which on a radial plane of the wheelis. in the state of rest, of substantially circular shape, is guided by arms I! secured in it periphery and pivotally mounted on a support ll-Ita carried by the web I2 of the wheel.

While I have, in the above description. disclosed what I deem to be practical and eificient embodiments of the present invention, it should be well understood that I do not wish to be limited thereto as there might be changm made in the arrangement, di-position and form of the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

1. A device for controlling the deformations of a non-extensible flexible band adapted constantly to maintain said band in arcuate form, comprising a pluraity of arms fixed to said band and pivoted to a common central piece at points located thereon along a hyperbolic spiral having a parameter equal to the radius of the circle formed by said band in its mean position, the angles of fixation of said arms to said band being such that said arms, in said mean position, are tangential to said spiral.

2. In comblnafion with a support, a non-extensible flexible band wound in the form of a circle freely movable with respect to said support, a common central piece pivoted to said support about an axis perpendicular to the plan of said band, a plurality of arms carried by said band at diflerent points thereof so as to make fixed angles therewith at said points, and means for pivoting said arms to said common central piece at respective points thereof located along a hyperbolic spiral formed on said piece in a plane parallel to that of said band and having its pole located on said axis and its parameter equal to the radius of the circle formed by said band in the mean position thereof, the angles of said arms with said band being such that said arms, in the mean position of said band, are tangent to said spiral, whereby, under the effect of the external forces acting thereon, said band remains wound in the form of a circle having its center at the pole of said spiral.

3. In combination with a support, a non-extensible flexible bandwound in the form of a circle,

a common central piece pivoted to said support about an axis perpendicular to the plane of said band, a plurality of arms carried by said band at different points thereof so as to make fixed angles therewith at said points, and means for pivoting said arms to said common central piece at respective points thereof located along a hyperbolic spiral formed on said piece in a plane parallel to that of said band and having its pole located on said axis and its parameter equal to the radius of the circle formed by said band in the mean position thereof, the angles of said arms with said band being such that said arms, in the mean position of said band, are tangent to said spiral, whereby, under the eflect of the external forces acting thereon, said band remains wound in the form of a circle having its center at the pole of said spiral.

4. The combination of a non-extensible flexible band wound in the form of a circle, at leasttwo central pieces pivoted to each other about an axis perpendicular to the plane of said band, a plurality of arms carried by said band at diiferent points thereof so as to make flxed angles therewith at said points, means for pivoting some of said arms to one of said central pieces at respective points thereof located along a hyperbolic spiral formed on said piece in a plane parallel to that of said band and having its pole located on said axis and its parameter equal to the radius of the circle formed by said band in the mean position thereof, and means for pivoting the remainder of said arms to the other central piece at respective points thereof located along a hyperbolic spiral formed on said piece in a plane parallel to that of said band and having its pole located on 7 said axis and the same parameter, the angles of said arms with said band being such that said arms, in the. mean position of said band, are tangent to their spirals, respectively, whereby, under" the eflect of external forces acting thereon, said band remains wound in the form of a circle having its center at the pole of .said spiral.

6. 'l'he combination of a non-extensible flexible band wound in the form of a circle, a common central piece, a plurality of arms carried by said band at different points thereof so as to make fixed angles therewith at said points, and means for pivoting some of said arms to said common central piece at respective points thereof located along a hyperbolic spiral formed on said piece in a plane parallel to that of said band and having its pole located on said axis and its parameter equal to the radius of the circle formed by said band in the mean position thereof, and means for pivoting the remainder of said arms to said piece at respective points thereof located along a hyperbolic spiral symmetrical of the first mentioned one with respect to the polar axis thereof, the angles of said arms with said band being such that said arms, in the mean position of said band, are tangent to their respective spirals whereby, under the effect of external forces acting thereon, said band remains wound in the form of a circle having the center at the pole of said spiral.

6. A resilient wheel which comprises, in combination, a non-extensible flexible rim wound in the form of a circle, a common hub piece, a plurality of arms carried by said rim at different points thereof so as to make flxed angles therewith at said points, means for pivoting said arms to said hub piece at respective points thereof located along a hyperbolic spiral formed thereon and having a parameter equal to the radius of the circle formed by said rim in the mean position thereof, the angles of said arms with said rim being such that said arms, in the mean position of said rim, are tangent to said spiral, and a wheel axle passing through the pole of said spiral.

7. A device of the character described which includes at least one non-extensible flexible arcuate part adapted to undergo variations of radius, comprising, a common central piece, a plurality of arms carried by said arcuate part at different points thereof so as to make fixed angles therewith at said points, and mechanical means for connecting said arms to said common central piece at respective points located thereon along a hyperbolic spiral having a parameter equal to the radius of the are formed by the arcuate part in its mean position, the angles of fixation being such that said arms, in said mean position, are tangential to said spiral.

- RAYMOND SAULNIER.

REFERENCES CITED The following references are of record in the me of this patent:

UNITED STATES PATENTS Jakobsen July 11, 1933 

